METHODOLOGY DEVELOPMENTS TO SUPPORT DYNAMIC RESERVOIR ASSESSMENT FOR CO2 GEOLOGICAL STORAGE IN CARBONATE RESERVOIRS

Some of the most important Greenhouse Gas (GHG) producers in North America, such as cement plants, are located in sedimentary basins where reservoir units potentially enable geological storage of CO₂. The environmental impact of such producers is a serious concern for several Canadian provinces including Ontario and Quebec, where the cement industry represents up to 7% of provincial CO₂ emissions. Our project goal is to develop, at the lab scale, new methodologies to better characterize the reservoir sequestration potential of sedimentary units at depth, and particularly for carbonate units that are even more unpredictable due to their natural complexity. After a thorough review of the literature, two experimental setups were designed and a set of 5 reference lithologies were chosen to represent the range of porosity and permeability found in Canadian sedimentary basins. The first setup is made to assess geochemical reactivity of sedimentary rocks after CO₂ injection, using a carbonation reactor. Using a CO₂ gas tank and a high-pressure metering pump, specific pressure and temperature conditions (1200-1500 psi; 40-60°C) are reached to work at CO₂ supercritical state. CO₂ is injected into brine saturated samples placed in the reactor, and the reaction is maintained for several days. Different measurements (e.g. petrophysical properties, chemical compositions, conventional petrography, micro-CT imaging) are made before and after on both the rock samples and the saturating brines. The second experimental setup is a geophysical monitoring experiment, using a NMR type core holder compatible with X-ray imaging. To conduct the acoustic measurements the pulse transmission method was selected (resonance frequency of 1 MHz). Two ceramic piezo rings are used, one transmission and the other for signal recording. Due to limitations associated with the core holder design, different options had to be tested in order to find the best piezo and electrical resistivity connections possible. At this point, signal acquisitions were a success and are working properly to measure the electro-elastic properties of the sample in a dry state, under reservoir conditions (1500 psi; 40°C). More developments are being made to successfully record electro-elastic properties under flooding conditions.